<template>
  <div class="delete">
    <div class="slider">
      <div class="content"
           @touchstart='touchStart'
           @touchmove='touchMove'
           @touchend='touchEnd'
           :style="deleteSlider"
      >
        <slot></slot>
      </div>
      <div class="remove active" ref='remove' @click.stop="handleClick">
        删除
      </div>
    </div>
  </div>
</template>

<script type="text/ecmascript-6">
  export default {
    props: {
      propE: {
        type: Object,
        default: function () {
        }
      }
    },
    data() {
      return {
        startX: 0,  //触摸位置
        endX: 0,   //结束位置
        moveX: 0,  //滑动时的位置
        disX: 0,  //移动距离
        deleteSlider: '',//滑动时的效果,使用v-bind:style="deleteSlider"
      }
    },

    methods: {
      handleClick(v) {
        this.$emit('msg-from-child', this.val);
        this.deleteSlider = "transform:translateX(0px)";
      },
      touchStart(ev) {
        ev = ev || event;
        //tounches类数组，等于1时表示此时有只有一只手指在触摸屏幕
        if (ev.touches.length == 1) {
          // 记录开始位置
          this.startX = ev.touches[0].clientX;
        }
      },
      touchMove(ev) {
        ev = ev || event;
        //获取删除按钮的宽度，此宽度为滑块左滑的最大距离
        let wd = this.$refs.remove.offsetWidth;
        if (ev.touches.length == 1) {
          // 滑动时距离浏览器左侧实时距离
          this.moveX = ev.touches[0].clientX;

          //起始位置减去 实时的滑动的距离，得到手指实时偏移距离
          this.disX = this.startX - this.moveX;
          // 如果是向右滑动或者不滑动，不改变滑块的位置
          if (this.disX < 0 || this.disX == 0) {
            this.deleteSlider = "transform:translateX(0px)";
            // 大于0，表示左滑了，此时滑块开始滑动
          } else if (this.disX > 0) {
            //具体滑动距离我取的是 手指偏移距离*5。
            this.deleteSlider = "transform:translateX(-" + this.disX * 5 + "px)";

            // 最大也只能等于删除按钮宽度
            if (this.disX * 5 >= wd) {
              this.deleteSlider = "transform:translateX(-" + wd + "px)";

            }
          }
        }
      },
      touchEnd(ev) {
        console.log(ev);
        ev = ev || event;

        let wd = this.$refs.remove.offsetWidth;
        if (ev.changedTouches.length == 1) {
          let endX = ev.changedTouches[0].clientX;

          this.disX = this.startX - endX;
          //如果距离小于删除按钮一半,强行回到起点

          if ((this.disX * 5) < (wd / 2)) {

            this.deleteSlider = "transform:translateX(0px)";
          } else {
            //大于一半 滑动到最大值
            this.deleteSlider = "transform:translateX(-" + wd + "px)";
          }
        }
      }
    }
  }
</script>

<style scoped lang="less" rel="stylesheet/less">
  .slider {
    width: 100%;
    height: 100px;
    position: relative;
    user-select: none;

    .content {
      position: absolute;
      left: 0;
      right: 0;
      top: 0;
      bottom: 0;
      background: #fff;
      z-index: 100;
      //  设置过渡动画
      transition: 0.3s;

    }

    .remove {
      position: absolute;
      width: 80px;
      height: 80px;
      background: #e96775;
      right: 0;
      top: 18px;
      color: #fff;
      text-align: center;
      font-size: 17px;
      line-height: 80px;
    }
  }

</style>
